I discovered this whilst trying out migrations via symfony. I added a datetime field to my schema.yml and generated the migrations, but upon running the migration I got the following error:

SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '()' at line 1. Failing Query: "ALTER TABLE order_item ADD purchased_at datetime()"

Ok, I might have been being dumb here. I've just checked the doctrine documentation for defining the schema (http://www.doctrine-project.org/documentation/manual/1_2/en/defining-models) and there's no mention of a datetime or text field (I've just realised that I should have used string instead of text anyway), but datetime still works as a column type so shouldn't it be documented?